Corrosion-induced casing leaks are a pervasive problem in many oil fields. While such leaks are a nuisance in production wells, they pose an economic and legal problem in injection wells. From a regulatory standpoint, the principal issue is the potential hazard of contamination of potable water supplies by leaking injection wells. For instance, the Texas Railroad Commission requires that active injection wells pass a casing integrity test. The test is conducted by filling the annulus between the well casing and tubing with water, pressurizing the system to at least 500 psi and monitoring the casing surface pressure for a 30 minute interval. If, during this time period, the casing pressure declines by more than 25 psi, the well fails the test. Only a very small fissure in a well casing is required to cause a well to fail this standard.
It is currently common practice in the oil industry to attempt to plug such casing leaks by a process called a "cement squeeze." In this process, a cement slurry is pumped into an isolated section of the well bore casing and pressurized to displace the cementitious material through the leaks to a position behind the casing. Well tubing and packers are retrieved prior to cement setting. Upon setting of the cement, a plug in the wellbore is created which must be drilled out and the tubing rerun in the hole.